Apparatus for cleaning charged particles, such as dust, from surfaces of objects are well known in the art. Existing cleaners are most effective for cleaning particles from substantially flat surfaces, such as web. Referring to FIG. 1, objects 1 having generally irregular or undulating surface features 2, e.g., non-planar surfaces, present a special challenge to clean because such surfaces have a plurality of features 2 that makes it difficult to dislodge particles using existing techniques.
In the process of manufacturing articles comprising polymeric materials, such as camera components, electrostatic charges inevitably are produced on the surface of the components. It is well known that these charges become sites for attracting oppositely charged ambient particles, such as dirt and other contaminants that can effect product quality if not cleaned prior to assembly.
Similarly, recyclable cameras, which are returned to the manufacturer for refurbishing, accumulate dirt and other undesirable particles that must eventually be cleaned during refurbishing. When the camera shells are opened at photofinishers for processing, ambient particles, in the form generally of dirt, can accumulate inside the cameras. Further, camera storage and the recycling process can expose the re-useable components of the camera to fibers and particles large enough to enter the film exposure window resulting in shadow images of these particles and fibers on the customer's pictures. Therefore, refurbishable camera components must undergo some level of cleaning to prevent such particles from accumulating on functionally sensitive features of the camera that could adversely effect product quality and performance.
Present systems for cleaning objects having generally irregular, undulating, surface features, such as recyclable cameras components, prior to refurbishing, use air nozzles with ionizing emitters to attempt to neutralize the static charge from the camera components and blow the particles off the discharged surfaces. In these systems, an overhead duct with a fan and filter removes the dislodged particles from the cleaning system. A significant shortcoming of these existing cleaning systems is that they are much too inefficient to operate. Such cleaning systems require a large volume of air to prevent dust recontaminating the cameras during cleaning because the particles removal duct is arranged overhead. This typically results in large volumes of dust-laden air being drawn from the surrounding room air into the cleaning device. Moreover, given the directional nature of the air nozzles, air is directed not only upwardly, but also inwardly from the entrance of the cleaning enclosure to the manufacturing environment due to a negative pressure region. Further, air propagates along the direction of the air nozzles, down the production line conveyor bearing the object to be cleaned. As a result, there is a high risk of re-contaminating the cameras after cleaning. Further, we have observed with existing cleaning processes, that dust would generally settle on the overhead filter and then migrate in large clumps downwardly towards and onto the cameras being cleaned.
Another existing apparatus for cleaning objects having generally irregular, undulating surface features, such as photographic camera parts, uses a pair of low volume air nozzles with ionizing emitter elements, followed by exhausting the air with a high volume air transvector exhaust device. The transvector exhaust device uses a small amount of compressed air to generate a larger volume of air. The low volume ionizing air nozzles were angled down the product conveyor towards the exhaust device, and both were mounted in a tunnel-like configuration. This design was also unsatisfactory, as the air nozzles did not provide enough force to dislodge particles and neutralize the electrostatic bonding force between the particles and the electric field intensities on the camera. This was the case even though the electrostatic charge was sufficiently reduced on the surface of the camera. More damaging, the transvector was drawing a large volume of room air into the chamber, and because of the directionality of the air from the nozzles to the transvector, large volumes of dirty air was being discharged down the conveyor belt.
Those skilled in the relevant art will appreciate that air nozzle or curtain cleaning devices are well known in the field. They are, however, exclusively used for cleaning substantially flat surfaces of articles, such as fabrics, film rolls and sheets, and other such web materials, as well as recording disks. This is because the air must be forced onto the surface of the object to be cleaned at an angle in order to provide enough force to dislodge the particle. In addition, for certain cleaning applications, a vacuum system must be employed to remove the particles from the cleaning enclosure so as to prevent re-contamination of the object being cleaned. Objects having irregular surface features, i.e., three dimensional or surfaces having protuberances such as camera components, do not allow intimate enough location for effective cleaning, and present too many angles to an air knife to be effective.
U.S. Pat. No. 4,594,748, by Warfvinge, Jun. 17, 1986; U.S. Pat. No. 5,491,602, by Horn et al., Feb. 13, 1996; U.S. Pat. No. 4,003,226, by Holdsworth, Jan. 18, 1977; and U.S. Pat. No. 4,198,061, by Dunn, Apr. 15, 1980; each discloses an apparatus for removing dust from generally flat surfaces, such as film rolls, fabric rolls, records, belts and other basically two-dimensionally surfaces. A major shortcoming of each of these cleaning devices is that they have proven woefully inadequate for cleaning objects, like camera components, having irregular features (non-planar) and surfaces.
Therefore, a need persists in the art for an apparatus and method for cleaning particles from objects having generally irregular, undulating, surface features that reduces the chances of object recontamination, will not impede assembly or packaging process speeds, and provides a localized clean environment to prevent further recontamination.